JP5986757B2 - Magnetorheological fluid shock absorber - Google Patents

Description

  The present invention relates to a magnetorheological fluid shock absorber using a magnetorheological fluid whose apparent viscosity changes due to the action of a magnetic field.

  As a shock absorber mounted on a vehicle such as an automobile, there is a shock absorber that changes a damping force by applying a magnetic field to a flow path through which the magnetorheological fluid passes to change an apparent viscosity of the magnetorheological fluid. In Patent Document 1, when a piston assembly including a piston core having a coil wound around the outer periphery and a piston ring disposed on the outer periphery of the piston core slides in the cylinder, the piston core is disposed between the piston core and the piston ring. A magnetorheological fluid damper is disclosed in which a magnetorheological fluid passes through a flow path formed in the above.

JP 2008-175364 A

  However, in the magnetorheological fluid shock absorber of Patent Document 1, in order to arrange the piston ring in a predetermined position with respect to the piston core, a pair of plates that clamp the piston ring in the axial direction are provided, and each plate is attached to a nut. It is fixed by fastening. As described above, since the piston ring is sandwiched and fixed from both ends by the plate and the nut, the total length of the piston assembly is increased, and the stroke length of the piston assembly may be shortened.

  The present invention has been made in view of the above problems, and an object thereof is to shorten the total length of the piston of the magnetorheological fluid shock absorber.

The present invention includes a cylinder in which a magnetorheological fluid whose viscosity is changed by the action of a magnetic field is sealed, a piston that is slidably disposed in the cylinder and that defines a pair of fluid chambers in the cylinder, and the piston A piston rod that is connected to the piston rod and extends to the outside of the cylinder, wherein the piston is attached to an end of the piston rod, and a piston core provided with a coil on an outer periphery thereof; A flux ring that surrounds the outer periphery of the piston core and forms a magneto-rheological fluid flow path between the piston core and an annularly formed outer periphery of the piston rod, and is attached to one end of the flux ring And an axial position relative to the piston rod, and the plate is disposed between the piston core and the piston rod. It is assumed that and a stopper for lifting.
The piston further includes a retaining ring that is fitted to the inner periphery of the stopper and fixes the stopper in the axial direction.
The piston core is attached to an end of the piston rod, the first core that contacts the plate, the coil assembly provided with the coil on the outer periphery, and the coil assembly between the first core. And a second core for clamping, and a fastening member for fastening the second core and the coil assembly to the first core.

  In the present invention, the plate attached to one end of the flux ring is sandwiched between the piston core attached to the end of the piston rod and the stopper whose axial position is defined with respect to the piston rod. Thereby, a flux ring is fixed to an axial direction to a piston core. Therefore, it is not necessary to provide another member protruding in the axial direction from the other end of the flux ring in order to define the axial position of the flux ring. Therefore, the total length of the piston of the magnetorheological fluid shock absorber can be shortened.

It is sectional drawing of the front of the magnetorheological fluid shock absorber concerning an embodiment of the invention. It is a left view of the piston in FIG. It is a right view of the piston in FIG.

  Embodiments of the present invention will be described below with reference to the drawings.

  First, an overall configuration of a magnetorheological fluid shock absorber 100 according to an embodiment of the present invention will be described with reference to FIG.

  The magnetorheological fluid shock absorber 100 is a damper whose damping coefficient can be changed by using a magnetorheological fluid whose viscosity changes by the action of a magnetic field. The magnetorheological fluid shock absorber 100 includes a cylinder 10 in which a magnetorheological fluid is sealed, a piston 20 that is slidably disposed in the cylinder 10, and a piston 20 that is connected to the piston 20 and extends to the outside of the cylinder 10. A piston rod 21.

  The cylinder 10 is formed in a bottomed cylindrical shape. The magnetorheological fluid sealed in the cylinder 10 has an apparent viscosity that is changed by the action of a magnetic field, and is a liquid in which fine particles having ferromagnetism are dispersed in a liquid such as oil. The viscosity of the magnetorheological fluid changes according to the strength of the applied magnetic field, and returns to its original state when the magnetic field is no longer affected.

  The piston 20 defines a fluid chamber 11 and a fluid chamber 12 in the cylinder 10. The piston 20 has an annular flow path 22 that allows the magnetorheological fluid to move between the fluid chamber 11 and the fluid chamber 12. The piston 20 can slide in the cylinder 10 when the magnetorheological fluid passes through the flow path 22. The configuration of the piston 20 will be described later in detail.

  The piston rod 21 is formed coaxially with the piston 20. The piston rod 21 has one end 21 a fixed to the piston 20 and the other end 21 b extending to the outside of the cylinder 10. The piston rod 21 is formed in a bottomed cylindrical shape in which one end 21a is opened and the other end 21b is closed. A pair of wires (not shown) for supplying a current to a coil 33a of the piston 20 described later is passed through the inner periphery 21c of the piston rod 21. On the outer periphery in the vicinity of one end 21 a of the piston rod 21, an annular shape formed in a shape corresponding to the outer shape of the C ring 51 corresponding to a position where a male screw 21 d screwed with the piston 20 and a C ring 51 described later is provided. A groove 21e is provided.

  Next, the configuration of the piston 20 will be described with reference to FIGS. 1 to 3.

  The piston 20 is attached to the end of the piston rod 21 and has a piston core 30 provided with a coil 33 a on the outer periphery thereof, and surrounds the outer periphery of the piston core 30 to form a magnetic viscous fluid flow path 22 between the piston core 30. A flux ring 35. The piston 20 is formed in an annular shape, is disposed on the outer periphery of the piston rod 21 and is attached to one end 35 a of the flux ring 35, and an axial position is defined between the piston rod 21 and the piston core 30. The stopper 50 which clamps the plate 40, and the C ring 51 as a retaining ring which is fitted to the inner periphery of the stopper 50 and fixes the stopper 50 in an axial direction are provided.

  The piston core 30 includes a first core 31 attached to the end of the piston rod 21, a coil assembly 33 provided with a coil 33 a on the outer periphery, and a second core 32 that sandwiches the coil assembly 33 between the first core 31. And a pair of bolts 30a as fastening members for fastening the second core 32 and the coil assembly 33 to the first core 31.

  The first core 31 has a large-diameter portion 31a whose outer periphery faces the inner periphery of the flux ring 35, a small-diameter portion 31b that has a smaller diameter than the large-diameter portion 31a, and a through-hole 31c that penetrates the center in the axial direction. And have.

  The large diameter part 31a is formed in a cylindrical shape. The outer periphery of the large diameter portion 31a faces the flow path 22 through which the magnetorheological fluid passes. The large diameter portion 31 a contacts the coil assembly 33. A cylindrical portion 33b of a coil assembly 33 to be described later is inserted and fitted into the through hole 31c of the large diameter portion 31a. The large-diameter portion 31a is formed with a pair of female screws 30b into which the bolts 30a are screwed.

  The small diameter portion 31b is formed coaxially with the large diameter portion 31a. The small diameter portion 31b is formed in a cylindrical shape protruding in the axial direction from the flux ring 35. On the inner periphery of the small diameter portion 31b, a female screw 31d that is screwed with the male screw 21d of the piston rod 21 is formed. The piston core 30 is fastened to the piston rod 21 by screwing the male screw 21d and the female screw 31d.

  An annular step portion 31e is formed on the outer periphery of the end portion continuous with the large diameter portion 31a of the small diameter portion 31b. The step portion 31 e is for the plate 40 to come into contact with the stopper 50 and sandwich the plate 40 therebetween.

  The second core 32 includes a large-diameter portion 32a whose outer periphery faces the inner periphery of the flux ring 35, a small-diameter portion 32b formed at one end of the large-diameter portion 32a with a smaller diameter than the large-diameter portion 32a, and a bolt 30a. It has a through-hole 32c that penetrates, and a deep-sinking portion 32d that engages with the head of the bolt 30a.

  The large diameter portion 32a is formed in a cylindrical shape. The large diameter portion 32 a is formed to have the same diameter as the large diameter portion 31 a of the first core 31. The outer periphery of the large-diameter portion 32a faces the flow path 22 through which the magnetorheological fluid passes. The large diameter portion 32 a is formed so that the end surface facing the fluid chamber 12 is flush with the other end 35 b of the flux ring 35.

  The small diameter part 32b is formed in a cylindrical shape coaxial with the large diameter part 32a. The small diameter portion 32b is formed to have the same diameter as the inner periphery of the coil mold portion 33d of the coil assembly 33 described later, and is fitted to the inner periphery of the coil mold portion 33d.

  A pair of through holes 32c are formed penetrating the second core 32 in the axial direction. The through hole 32c is formed to have a larger diameter than the diameter of the threaded portion of the bolt 30a. The through hole 32c is formed so as to be coaxial with the female screw 30b of the first core 31 in a state where the piston core 30 is assembled.

  The deep countersink 32d is formed at the end of the through hole 32c. The deep-sinking portion 32d is formed to have a larger diameter than the through hole 32c and a larger diameter than the head of the bolt 30a. The deep countersink 32d is formed to a depth that can completely accommodate the head of the bolt 30a. When the bolt 30 a inserted through the through hole 32 c is screwed into the female screw 31 d of the first core 31, the bottom surface of the deep seat retraction part 32 d is pressed against the first core 31, and the second core 32 is pressed against the first core 31.

  The coil assembly 33 is formed by molding in a state where the coil 33a is inserted. The coil assembly 33 includes a cylindrical portion 33b that fits in the through hole 31c of the first core 31, a flat plate portion 33c that is sandwiched between the first core 31 and the second core 32, and a coil 33a. A coil mold portion 33d.

  The coil 33a forms a magnetic field by a current supplied from the outside. The strength of the magnetic field increases as the current supplied to the coil 33a increases. When a current is supplied to the coil 33a and a magnetic field is formed, the apparent viscosity of the magnetorheological fluid flowing through the flow path 22 changes. The viscosity of the magnetorheological fluid increases as the magnetic field generated by the coil 33a increases.

  As for the cylindrical part 33b, the front-end | tip part 33e fits to the inner periphery of the piston rod 21. As shown in FIG. A pair of wires for supplying a current to the coil 33a is drawn from the tip of the cylindrical portion 33b. An O-ring 34 as a sealing member is provided between the tip 33e of the cylindrical portion 33b and the one end 21a of the piston rod 21.

  The O-ring 34 is compressed in the axial direction by the large diameter portion 31 a of the first core 31 and the piston rod 21, and is compressed in the radial direction by the distal end portion 33 e of the coil assembly 33 and the piston rod 21. Thereby, the magnetorheological fluid that has entered between the outer periphery of the piston rod 21 and the first core 31 or between the first core 31 and the coil assembly 33 flows out to the inner periphery of the piston rod 21 and leaks out. Is prevented.

  The flat plate portion 33c is formed in a coaxial disk shape continuously to the proximal end portion of the cylindrical portion 33b. A pair of wires for supplying a current to the coil 33a passes through the flat plate portion 33c and the cylindrical portion 33b. The flat plate portion 33c has a through hole 33f through which the bolt 30a passes.

  The through hole 33 f is formed to have the same diameter as the through hole 32 c of the second core 32. The through hole 33f is formed to be coaxial with the female screw 30b of the first core 31 and to be continuous with the through hole 32c in a state where the piston core 30 is assembled.

  The coil mold portion 33d is erected in an annular shape from the outer edge portion of the flat plate portion 33c. The coil mold portion 33d is formed to protrude from the end of the coil assembly 33 opposite to the cylindrical portion 33b. The coil mold part 33 d is formed to have the same diameter as the large diameter part 31 a of the first core 31. The outer periphery of the coil mold portion 33d faces the flow path 22 through which the magnetorheological fluid passes. A coil 33a is provided inside the coil mold portion 33d.

  As described above, the piston core 30 is formed by being divided into three members of the first core 31, the second core 32, and the coil assembly 33. Therefore, only the coil assembly 33 provided with the coil 33a may be molded and sandwiched between the first core 31 and the second core 32. Therefore, it is easier to form the piston core 30 as compared to the case where the piston core 30 is formed as a single unit and the molding operation is performed.

  In the piston core 30, the first core 31 is fixed to the piston rod 21, but the coil assembly 33 and the second core 32 are only fitted in the axial direction. Therefore, in the piston 20, the second core 32 and the coil assembly 33 are fixed so as to be pressed against the first core 31 by fastening a pair of bolts 30 a.

  The bolt 30 a is inserted through the through hole 32 c of the second core 32 and the through hole 33 f of the coil assembly 33 and is screwed into the female screw 30 b of the first core 31. The bolt 30a presses the bottom surface of the deep-feeding portion 32d toward the first core 31 by the fastening force. As a result, the coil assembly 33 is sandwiched between the second core 32 and the first core 31, and the piston core 30 is integrated.

  Thus, the second core 32 and the coil assembly 33 are pressed against the first core 31 and fixed only by fastening the bolt 30a. Therefore, the piston core 30 can be easily assembled.

  The flux ring 35 is formed in a substantially cylindrical shape. The outer periphery of the flux ring 35 is formed to have substantially the same diameter as the inner periphery of the cylinder 10. The inner periphery of the flux ring 35 faces the outer periphery of the piston core 30. The inner periphery of the flux ring 35 is formed to have a larger diameter than the outer periphery of the piston core 30, and the flow path 22 is formed between the inner periphery of the flux ring 35 and the piston core 30. The flux ring 35 is fixed to the piston core 30 via the plate 40 so as to be coaxial with the piston core 30.

  The flux ring 35 has a small diameter portion 35c formed on the inner periphery of the one end 35a and into which the plate 40 is fitted. The small diameter portion 35c is formed with a small diameter as compared with other portions of the flux ring 35 so that the plate 40 fits on the outer periphery.

  The plate 40 supports the one end 35a of the flux ring 35 with respect to the piston core 30 and defines the position in the axial direction. The outer periphery of the plate 40 is formed to have the same diameter as the outer periphery of the flux ring 35.

  As shown in FIG. 2, the plate 40 has a plurality of flow paths 22 a that are through holes communicating with the flow paths 22. The flow path 22a is formed in a circular shape and is arranged in an annular shape at equal intervals.

  A through hole 40 a into which the small diameter portion 31 b of the first core 31 is fitted is formed on the inner periphery of the plate 40. The plate 40 is ensured to be coaxial with the first core 31 by fitting the small diameter portion 31b into the through hole 40a.

  On the outer periphery of the plate 40, an annular flange 40b that fits into the small diameter portion 35c of the one end 35a of the flux ring 35 is formed. The flange portion 40 b is formed to protrude toward the flux ring 35. The collar part 40b is fixed by brazing with the small diameter part 35c. Instead of brazing, the plate 40 and the flux ring 35 may be fixed by welding or fastening.

  The plate 40 is pressed and clamped against the stopper 50 by the fastening force of the piston core 30 with respect to the piston rod 21. Thereby, the position of the axial direction with respect to the piston core 30 of the flux ring 35 fixed to the plate 40 will be prescribed | regulated.

  The stopper 50 is formed in a substantially cylindrical shape and is fitted to the outer periphery of the small diameter portion 31 b of the first core 31. The stopper 50 is in contact with the plate 40 at the tip 50a. The stopper 50 has a large-diameter portion 50c that fits on the outer periphery of the small-diameter portion 31b on the inner periphery of the tip portion 50a. The stopper 50 has a tapered portion 50d formed in a tapered shape whose diameter is increased toward the end surface on the inner peripheral surface of the base end portion 50b.

  The large diameter portion 50 c is formed facing the plate 40. The large diameter portion 50 c is formed with an inner diameter that is substantially the same as the outer diameter of the plate 40. The end surface of the distal end portion 50 a of the large diameter portion 50 c is formed in parallel with the end surface of the plate 40 and is in surface contact with the plate 40.

  The tapered portion 50 d abuts on the C ring 51. In a state where the taper portion 50 d is in contact with the C ring 51, the stopper 50 can no longer move in the axial direction toward the other end 21 b of the piston rod 21.

  The C ring 51 is a ring formed in a circular cross section. The C-ring 51 is formed in a C-shaped ring shape with a part of the circumference opening. The C-ring 51 is fitted into the annular groove 21e by a force that tends to shrink to the inner periphery. The C ring 51 abuts on the tapered portion 50d of the stopper 50 and defines the axial position of the proximal end portion 50b of the stopper 50.

  As described above, the plate 40 attached to the one end 35a of the flux ring 35 includes the piston core 30 attached to the end of the piston rod 21 and the stopper 50 whose axial position is defined with respect to the piston rod 21. It is pinched. Thereby, the flux ring 35 is fixed to the piston core 30 in the axial direction. Therefore, it is not necessary to provide another member protruding in the axial direction from the other end 35b of the flux ring 35 in order to define the axial position of the flux ring 35. Therefore, the total length of the piston 20 of the magnetorheological fluid shock absorber 100 can be shortened.

  Below, an example of the assembly procedure of piston 20 is demonstrated.

  First, the piston core 30 is assembled. First, the coil assembly 33 is attached to the first core 31. The cylindrical portion 33b of the coil assembly 33 is inserted into the through hole 31c of the first core 31 from the large diameter portion 31a side, and a pair of wires for supplying current to the coil 33a is connected to the small diameter portion 31b side of the through hole 31c of the first core 31. Pull out from.

Next, the second core 32 is attached to the coil assembly 33. It attaches so that the small diameter part 32b of the 2nd core 32 may fit in the inner periphery of the coil mold part 33d of the coil assembly 33. FIG. Then, after inserting the pair of bolts 30 a through the through hole 32 c of the second core 32 and the through hole 33 f of the coil assembly 33, the pair of bolts 30 a is screwed into the female screw 30 b of the first core 31. By assembling the bolt 30a, the assembly of the piston core 30 is completed.

  In parallel with the assembly of the piston core 30, the flux ring 35 and the plate 40 are assembled together. Specifically, the flange portion 40b of the plate 40 is fitted to the small diameter portion 35c of the flux ring 35, and brazing is performed.

  Then, the plate 40 assembled integrally with the flux ring 35 is assembled to the piston core 30. Specifically, the plate 40 is fitted on the outer periphery of the small diameter portion 31 b of the first core 31 of the piston core 30 and brought into contact with the step portion 31 e of the first core 31. In this state, the plate 40 is only in contact with the stepped portion 31e and is not fixed in the axial direction.

  Next, the piston rod 21 and the stopper 50 are assembled. First, the C ring 51 is fitted into the annular groove 21 e of the piston rod 21. Then, the stopper 50 is fitted from one end 21 a of the piston rod 21. In the stopper 50, the C-ring 51 comes into contact with the tapered portion 50d of the inner peripheral surface of the base end portion 50b, and the position in the axial direction is defined.

  Finally, the piston rod 21 and the piston core 30 are assembled. Specifically, the internal thread 31 d of the first core 31 of the piston core 30 and the external thread 21 d of the piston rod 21 are screwed together. At this time, an O-ring 34 is inserted in advance between the tip 33e of the piston rod 21 and the one end 21a of the piston rod 21.

  When the piston core 30 is rotated with respect to the piston rod 21, the piston core 30 is assembled in advance between the step portion 31 e of the first core 31 of the piston core 30 and the tip portion 50 a of the stopper 50. The old plate 40 is clamped. Thereby, the assembly of the piston 20 is completed.

  Thus, the plate 40 is pressed against the stopper 50 and fixed by the fastening force of the piston core 30 to the piston rod 21 of the first core 31. Therefore, the piston 20 can be easily assembled only by fastening the piston core 30 to the piston rod 21. Moreover, since each member of piston 20 can be firmly fixed by the fastening force of piston core 30, rotation of each member is prevented and vibration is suppressed.

  In the present embodiment, the piston 20 is divided into three members including a first core 31, a second core 32, and a coil assembly 33. However, instead of this configuration, the first core 31 and the coil assembly 33 may be integrally formed as two members, or the second core 32 and the coil assembly 33 may be integrally formed as two members. Good.

  In addition to the assembly procedure described above, for example, only the first core 31 is fastened to the piston rod 21 so that the plate 40 is sandwiched between the stopper 50, and then the coil assembly 33 and the second core 32 are connected. It is also possible to assemble and fasten with bolts 30a.

  According to the above embodiment, the following effects are obtained.

  A plate 40 attached to one end 35 a of the flux ring 35 is sandwiched between a piston core 30 attached to the end of the piston rod 21 and a stopper 50 whose position in the axial direction is defined with respect to the piston rod 21. Thereby, the flux ring 35 is fixed to the piston core 30 in the axial direction. Therefore, it is not necessary to provide another member protruding in the axial direction from the other end 35b of the flux ring 35 in order to define the axial position of the flux ring 35. Therefore, the total length of the piston 20 of the magnetorheological fluid shock absorber 100 can be shortened.

  The piston core 30 is formed by being divided into three members including a first core 31, a second core 32, and a coil assembly 33. Therefore, only the coil assembly 33 provided with the coil 33a may be molded and sandwiched between the first core 31 and the second core 32. Therefore, it is easier to form the piston core 30 as compared to the case where the piston core 30 is formed as a single unit and the molding operation is performed.

  The plate 40 to which the flux ring 35 is fixed integrally is pressed against and fixed to the stopper 50 by the fastening force of the first core 31 of the piston core 30 to the piston rod 21. Therefore, the piston 20 can be easily assembled only by fastening the piston core 30 to the piston rod 21.

  The present invention is not limited to the above-described embodiment, and it is obvious that various modifications can be made within the scope of the technical idea.

  For example, in the magnetorheological fluid shock absorber 100, a pair of wires for supplying a current to the coil 33a passes through the inner periphery of the piston rod 21. Therefore, it is possible to eliminate the ground for allowing the current applied to the coil 33a to escape to the outside. However, instead of this configuration, only one wire for applying a current to the coil 33a may pass through the inside of the piston rod 21 and be grounded to the outside through the piston rod 21 itself.

100 Magnetorheological fluid shock absorber 10 Cylinder 11 Fluid chamber 12 Fluid chamber 20 Piston 21 Piston rod 21e Annular groove 22 Flow path 30 Piston core 30a Bolt (fastening member)
31 First core 32 Second core 33 Coil assembly 33a Coil 35 Flux ring 35a One end 35b Other end 40 Plate 50 Stopper 50a Tip 50b Base end 50d Taper 51 C ring (retaining ring)

Claims (5)

A cylinder in which a magnetorheological fluid whose viscosity is changed by the action of a magnetic field is enclosed;
A piston slidably disposed within the cylinder and defining a pair of fluid chambers within the cylinder;
A piston rod coupled to the piston and extending to the outside of the cylinder; and a magnetorheological fluid damper comprising:
The piston is
A piston core attached to the end of the piston rod and provided with a coil on the outer periphery;
A flux ring that surrounds the outer periphery of the piston core and forms a flow path of the magnetorheological fluid with the piston core;
A plate formed in an annular shape and disposed on the outer periphery of the piston rod, and attached to one end of the flux ring;
A stopper that defines an axial position with respect to the piston rod, and sandwiches the plate between the piston core;
A magnetorheological fluid shock absorber comprising: a retaining ring that is fitted to an inner periphery of the stopper and fixes the stopper in the axial direction . An annular groove is formed on the outer periphery of the piston rod corresponding to the position where the retaining ring is provided,
2. The magnetorheological fluid shock absorber according to claim 1, wherein the retaining ring is fitted into the annular groove by a force to be shrunk to an inner periphery . The retaining ring is formed in a C-shaped ring shape in which a part of the circumference is open,
The tip of the stopper abuts the plate,
3. The magnetic viscosity according to claim 1, wherein a taper portion that is formed in a tapered shape that expands toward an end surface and abuts against the retaining ring is formed at a base end portion of the stopper. Fluid shock absorber. The piston core is fastened to the piston rod;
4. The magnetorheological fluid shock absorber according to claim 1, wherein the plate is pressed and clamped against the stopper by a fastening force of the piston core . 5. A cylinder in which a magnetorheological fluid whose viscosity is changed by the action of a magnetic field is enclosed;
A piston slidably disposed within the cylinder and defining a pair of fluid chambers within the cylinder;
A piston rod coupled to the piston and extending to the outside of the cylinder; and a magnetorheological fluid damper comprising:
The piston is
A piston core attached to the end of the piston rod and provided with a coil on the outer periphery;
A flux ring that surrounds the outer periphery of the piston core and forms a flow path of the magnetorheological fluid with the piston core;
A plate formed in an annular shape and disposed on the outer periphery of the piston rod, and attached to one end of the flux ring;
An axial position with respect to the piston rod, and a stopper for sandwiching the plate with the piston core,
The piston core is
A first core attached to the end of the piston rod and in contact with the plate;
A coil assembly in which the coil is provided on the outer periphery;
A second core for sandwiching the coil assembly with the first core;
A magnetorheological fluid shock absorber comprising: a fastening member that fastens the second core and the coil assembly to the first core .

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